Core Python Programming (2nd Edition)

it can immediately make a connection to a server by using the socket's connect() method. When the
connection has been established, then it can participate in a dialog with the server. Once the client has
completed its transaction, it may close its socket, terminating the connection.
We present the code for tsTclnt.py in Example 16.2; it connects to the server and prompts the user for
line after line of data. The server returns this data timestamped, which is presented to the user by the
client code.
Example 16.2. TCP Timestamp Client (tsTclnt.py)
Creates a TCP client that prompts the user for messages to send to the server, gets them
back with a timestamp prefix, and displays the results to the user.
1 #!/usr/bin/env python
2
3 from socket import *
4
5 HOST = 'localhost'
6 PORT = 21567
7 BUFSIZ = 1024
8 ADDR = (HOST, PORT)
9
10 tcpCliSock = socket(AF_INET, SOCK_STREAM)
11 tcpCliSock.connect(ADDR)
12
13 while True:
14 data = raw_input('> ')
15 if not data:
16 break
17 tcpCliSock.send(data)
18 data = tcpCliSock.recv(BUFSIZ)
19 if not data:
20 break
21 print data
22
23 tcpCliSock.close()
Line-by-Line Explanation
Lines 13
After the Unix startup line, we import all the attributes from the socket module.
Lines 511
The HOST and PORT variables refer to the server's hostname and port number. Since we are running our
test (in this case) on the same machine, HOST contains the local hostname (change it accordingly if you
are running your server on a different host). The port number PORT should be exactly the same as what
you set for your server (otherwise there won't be much communication[!]). We also choose the same
buffer size, 1K.